.yellow{
    margin: 0 auto;
    width: 100px;
    height: 100px;
    background-color:yellow;
    text-align: center;
    line-height: 100px;
}
.yellowgreen{
    margin: 0 auto;
    width: 100px;
    height: 100px;
    background-color:yellowgreen;
    text-align: center;
    line-height: 100px;
}
.qing{
        margin: 0 auto;
        width: 100px;
        height: 100px;
        background-color:blue;
        text-align: center;
        line-height: 100px;
}
.blue{
    margin: 0 auto;
    width: 100px;
    height: 100px;
    background-color:skyblue;
    text-align: center;
    line-height: 100px;
}
.zi{
    margin: 0 auto;
    width: 100px;
    height: 100px;
    background-color:purple;
    text-align: center;
    line-height: 100px;
}